Diagnostic testing apparatus



FIG. 1 is a top, front, right perspective view of a diagnostic testing apparatus in accordance with my design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a right side elevational view thereof; and,

FIG. 7 is a left side elevational view thereof.

The broken lines shown form no part of the claimed design. 

CLAIM The ornamental design for a diagnostic testing apparatus, as shown and described. 